1. Technical Field
The present disclosure relates to a semiconductor memory device and, more particularly, to a sense amplifier circuit, a semiconductor memory device having a sense amplifier and a method of amplifying a signal.
2. Discussion of Related Art
A semiconductor memory device is used for storing data in various electronic products and applications. A sense amplifier circuit is used during a data input-output (I/O) procedure in the semiconductor memory device. The sense amplifier circuit includes a bit-line sense amplifier circuit amplifying voltages of a bit-line pair, a local sense amplifier circuit amplifying voltages of a local I/O line pail; and an I/O sense amplifier circuit amplifying voltages of a global I/O line pair.
As the load of an I/O sense amplifier circuit implemented with conventional voltage sense amplifiers is increased, the 110 sense amplifier circuit has difficulties in sensing voltage differences, because a distance between the I/O sense amplifier circuit and a memory cell array becomes longer. Usually, an I/O sense amplifier circuit implemented with current sense amplifiers may be used in order to obviate the above-mentioned problems. As an amplification gain is increased, an input resistance of the I/O sense amplifier circuit implemented with the current sense amplifiers may have a negative value, and thus the I/O sense amplifier circuit may be unstable. Another conventional I/O sense amplifier circuit for obviating this problem may include a current sense amplifier implemented with large-sized transistors and a differential amplifier coupled to output terminals of the current sense amplifier. When, sizes of transistors in the current sense amplifier are increased, however, the sizes of the I/O sense amplifier circuit are significantly increased and a current consumption is also increased.